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Facilitated ignition and detonation initiation of hydrogen-oxygen mixtures by ozone doping.
- Source :
-
Combustion & Flame . Dec2022, Vol. 246, pN.PAG-N.PAG. 1p. - Publication Year :
- 2022
-
Abstract
- This work computationally studies homogeneous and inhomogeneous ozone addition in hydrogen-oxygen ignition and transition to detonation, with emphasis on the ozone-induced two-stage behaviors in the chemical kinetics and wave dynamics. In 0D homogenous ignitions, ozone addition induces an additional first-stage reaction and substantially reduces the ignition delay time (IDT). At intermediate initial temperatures, e.g. T 0 = 600 K, a critical value, α cr , is identified to delineate different regimes for ozone fraction in the total oxidizer, α. Specifically, the first-stage ignition occurs several orders earlier than IDT for α < α cr , while the IDTs for two stages are comparable for α > α cr. Mechanistically, low-to-intermediate temperature HO 2 chemistry introduces a quasi-steady intermediate state in the former regime, whereas ozone reactions directly accelerate high-temperature H 2 O 2 reactions in the latter one. Furthermore, according to the Zel'dovich mechanism, ozone concentration non-uniformity can establish reactivity gradient and hence further initiate double spontaneous waves with multiple dynamics. Coherent coupling between the second-stage heat release and pressure (shock) wave can further evolve into detonation, whereas such synchronized enhancement is not observed in the first-stage ignition due to its large excitation time. Corresponding to the multi-timescales in 0D ignition, when the initial α interval are respectively below, across and above α cr , the low- and high- temperature reaction fronts always separate, first separate then merge, and always merge, respectively. It is also noted that at higher initial temperatures α cr decreases, and that the first-stage reaction becomes less concentrated. Consequently, detonation can be initiated with smaller amounts of ozone and is minimally influenced by the first-stage reaction. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00102180
- Volume :
- 246
- Database :
- Academic Search Index
- Journal :
- Combustion & Flame
- Publication Type :
- Academic Journal
- Accession number :
- 160632151
- Full Text :
- https://doi.org/10.1016/j.combustflame.2022.112474